Fix invalid pubkey panic #331
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added 16 commits
August 23, 2025 18:05
Prevents dmsg server crashes when handling clients with invalid public keys. Changes: - Modified noise DH function to use non-panic cipher methods (NewPubKey, NewSecKey, ECDH) instead of MustNewPubKey, MustNewSecKey, MustECDH - Added panic recovery in noise handshake to catch any remaining panics - Added panic recovery in server handleSession to prevent server crashes - Added panic recovery in server stream goroutines for additional safety - Added error logging for failed session creation Invalid public keys will now cause the handshake to fail gracefully instead of crashing the entire dmsg server process. The server will log the error and continue serving other clients. Fixes a 2+ year old issue where 'Invalid public key' panic would crash production dmsg servers.
Adds TestInvalidPublicKeyNoPanic to verify the server doesn't crash when receiving connections with invalid public keys during noise handshake. The test: 1. Sends malformed handshake data with invalid public key to server 2. Verifies server logs error and rejects connection gracefully 3. Confirms server continues to accept valid client connections This is a regression test for the 2+ year old panic bug that has been fixed in the previous commits.
- Use proper error handling for conn.Close() - Add nolint directives for intentionally ignored errors - Fix ineffectual assignment in test code
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Fixes #221
Summary of Changes
This panic:
was caused by cipher.MustNewPubKey() in the noise handshake DH function (pkg/noise/dh.go:26), which would
crash the entire server when a client sent an invalid public key.
Fixed Files (branch fix/invalid-pubkey-panic )
Defense in Depth Approach
The fix uses multiple layers:
• Root cause: DH function now handles invalid keys gracefully, returning empty bytes that will cause handshake to fail
• Handshake layer: Panic recovery catches any remaining panics and converts to errors
• Session layer: Panic recovery prevents session crashes from affecting the server
• Stream layer: Individual stream panics won't kill the session